Geothermal power generation specially catches the attention of the government and related industries of a country or district with rich geothermal resources. Compared with the conventional power generations such as solar and offshore wind power generations, the geothermal power generation has higher power generation efficiency and cost-effectiveness. In addition, the geothermal power has the feature of stable power supply and thus may serve as a baseload electric power. Especially, Taiwan and many other districts with rich geothermal resources can generate power with a lower total cost and overcome the problem of electric power shortage effectively. The geothermal power generation gradually replaces the nuclear or thermal power generation and reduces the emission of greenhouse gases to provide a better chance for sustainable human survival and development.
Geothermal fluids in many locations are situated at a status of appropriate working pressure and high stability. When the geothermal fluid reaches the Earth's surface, the outlet end pressure in a pipe flow maintains the geothermal fluid in two phases (saturated steam or over-saturated steam) in a compressible fluid state, and the geothermal fluid gushes out in a form of wet vapor which provide a sufficient working stability. Less than 5% of the world's geothermal fields produce dry steam directly. Although many districts have rich geothermal resources, yet most of them produce relatively low-temperature wet vapor geothermal fluid below 200° C., and the steam in the working fluid is below 20%. Therefore, finding a way of generating electric power by a wet vapor geothermal fluid effectively demands immediate attention and feasible solutions. Geothermal power generation definitely plays an important role in future energy autonomy and green economy.
According to the development in different countries and districts in the past two decades, the design of geothermal power generation plants is divided by the temperature of the geothermal fluid, and the geothermal power of a generation power generation facility is mainly divided by the temperature and the water-vapor state of a geothermal source into a dry steam type, a flash steam type, and a double-cycle type. Although the conventional dry steam type, flash steam type, and Organic Rankine Cycle (ORC) geothermal power generation system can accept the geothermal source (such as hot water, steam or vapor-liquid phased working fluid) to drive a turbine or expansion screw to link a power generator to generate electric power. However, the conventional geothermal power generation systems still has the following deficiencies that require further improvements: 1. For example, most of the geothermal resources in Taiwan are mixed fluid (hot water vapor and hot water) type wet vapor geothermal field, and the turbine of the conventional geothermal power generation system is not designed optimally with the features of such geothermal field. Although the flash geothermal power generation system may flash a portion of hot water into steam, only a general steam turbine is provided for bearing the drive of steam, and most of the non-flash hot water cannot be used for the power generation, thus resulting in a poor thermal efficiency and reducing the geothermal power generation efficiency. 2. Since the geothermal power generation systems only has one set of hot source spout, the geothermal fluid cannot be erupted effectively and uniformly to each blade of the turbine, and the mechanical efficiency of the turbine is reduced to lower the geothermal power generation efficiency. 3. The wet vapor geothermal fluid mixed with hot water vapor cannot be used completely. For example, the flash geothermal power generation system can just be used for pushing the turbine to push the steam and re-eject a large quantity of non-flash hot water, and the double-cycle type geothermal power generation system requires a heat exchanger and uses an expansion screw or an air turbine to withstand the drive of the gaseous working fluid in order to drive the power generator to generate electric power, and thus the heat exchanger loses much usable energy.
In view of the aforementioned drawbacks of the prior art, the inventor of the present invention based on years of experience to conduct extensive research and experiment, and finally provided a feasible solution to overcome the drawbacks of the prior art.